Priority is claimed on Japanese Patent Application No. 2007-185514, filed Jul. 17, 2007, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a seatbelt device in a vehicle having a pretensioner, in particular, to a pretensioner control at the time of a rear vehicular collision, or at the time of predicting a rear vehicular collision.
2. Description of the Related Art
Conventionally there has been known a seatbelt device in which the upper body of a passenger is restrained on a seat back before a rear vehicular collision occurs, by operating a pretensioner to wind up webbing when a rear vehicular collision is predicted, and at the time of the rear vehicular collision, forward movement of the upper body of the passenger from the seat back is enabled to a certain extent by correction for reducing the operation intensity of the pretensioner in accordance with the collision acceleration and so forth. The above seatbelt device prevents the head of the passenger from swinging forward due to rebound action after the rear vehicular collision (for example, refer to Japanese Patent No. 3796961).
However, there is a problem in the above conventional technique in that a relatively complex control is required in which when predicting a rear vehicular collision, the possibility of the rear vehicular collision is determined based on the approaching velocity of an object coming from behind, and when the rear vehicular collision occurs, a reduction correction value is calculated based on the collision acceleration and so forth.
Consequently, an object of the present invention is to provide a seatbelt device for a vehicle in which the amount of webbing winding is appropriately and simply controlled at the time of a rear vehicular collision or when a rear vehicular collision is predicted, and it is possible to suppress an excessive restraint of the webbing.